Indian Forest Service Examinatic .. fillzillill DETACHABLE
AGRICULTURAL ENGINEERING
Paper II
I Time Allowed Three Hours I I Maximum Marks 200 I
QUESTION PAPER SPECIFIC INSTRUCTIONS
Please read each of the following instructions carefully before attempting questions.
There are EIGHT questions in all out of which, FIVE are to be attempted.
Question no. 1 5 are compulsory. Out of the remaining SIX questions, THREE are to be attempted
selecting at least ONE question from each of the two Sections A and B.
Attempts of questions shall be counted in chronological order. Unless struck off, attempt ofa question
shall be counted even if attempted partly. Any page or portion of the page left blank in the answer book
must be clearly struck off.
All questions carry equal marks. The number of marks carried by a question/part is indicated against it.
Answers must be written in ENGLISH only.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Assume suitable data, if necessary and indicate the same clearly.
Neat sketches may be drawn, wherever required.
SECTION
l.(a)Draw the valve timing diagram of a four stroke tractor engine and explain. 8
l.(b)How many times the power of a four stroke engine increases or decreases if the diameter of
the piston is increased by 20 per cent and stroke length is reduced by 20 per cent, and all factors
remaining the same.
l.(c)Explain about solar cell and how electric current is produced in the cell. 8
l.(d)A hydraulic circuit uses 25 litres of fluid per minute. The fluid is supplied by a pump having a
fixed displacement of 12·5 cm3 per revolution driven at 3000 rpm. The pump has a volumetric
efficiency of 85 per cent and torque efficiency of 88 per cent. If the system pressure is set at
18 MPa by the relief valve, calculate the power required to drive the pump heat generated
owing to excess flow passing over the relief valve. 8
l.(e)Calculate (i)the volume of a biogas digester suitable for the output of five cows and
the power available from the digester. Retention time is 20 days, temperature 30°C,
dry matter available 2 kg/day per cow, biogas yield 0·24 m3 per kg. Burner efficiency is
60 per cent, methane proportion is 0·8. The heat of combustion of methane may be assumed to
be 28 MJ/m3 at standard temperature and pressure. The density of dry matter in the fluid may
be taken as 50kg/m3 8





Calculate the angle made by beam radiation with the normal to a flat plate collector on
December 1 at 9·00 am (local apparent time). The collector located at 28°35'N and 77°12'E
is tilted at an angle of 36 deg with the horizontal and is pointing due south. 10
With a neat sketch, explain Deenabandhu biogas plant. 10
A farmer erected a propeller type wind turbine. The diameter of the turbine is 120 m and
rotating at 40 rpm at maximum efficiency. On the farm, wind velocity of 15m/s is available
at one standard atmospheric pressure and l5°C. Calculate the total power density in the
wind stream the maximum obtainable power density the total power and the torque
and axial thrust. For air assume gas constant as 0·287 kJ/kgK. The efficiency of wind
turbine is 35 per cent. 10
What is pyrolysis and how gasifiers are biomass classified? 10

What are the functions of a carburettor and explain its different components. 10
In a diesel cycle, the compression of air starts at atmospheric pressure and 37°C temperature.
The compression ratio is 16:1. The cylinder has 10cm bore diameter and 12cm stroke length.
Calculate the air standard efficiency and net work done per cycle, if the addition of heat
at constant pressure ends at 5 per cent of stroke volume. Also find the increase or decrease in
air standard efficiency, if the fuel cut off ends at 20 per cent of the stroke length. Assume
Cv 0·718 kJ/kgK and characteristic gas constant as 287 J/kgK. 15
3.(c)Why a tractor is provided with a differential unit and how does it work 8
With a neat schematic diagram, classify the disc harrows based on their gang arrangement. 7

Explain the splash and force feed systems of lubrication in engines. 10
A bullock drawn single row planter has a wheel of 50cm diameter. The wheel shaft carries a
7 teeth sprocket which drives a 12 teeth sprocket on a counter shaft. Another 7 teeth sprocket
on the counter shaft drives a 12 teeth sprocket on a shaft carrying a roller with 4 cells on its
periphery for dropping of single seed per hill. Calculate total number of droppings along one
row in 10 minutes if the travelling speed is 2.5 km/h determine the horse power required to
pull the planter, when the cross-section of the furrow was 7·5 x 7·5 cm and soil resistance was
7kgr/cm2. 10
Explain the principle of working of a battery ignition system with the help of a circuit. 10
A motor car has a wheel base of 2·743 m and pivot centre of 1·065 m. The front and rear wheel
track is 1.217m. Calculate the correct angle of outside lock and turning radius of the outer front
and inner rear wheels when the angle of inside lock is 40 deg. 10

SECTION
5.(a)What are the principles of size reduction Derive an equation for energy and power requirement
in size reduction. 8
5.(b)What do you understand by standardization of milk? Explain Pearson's square method for
500 kg of milk having fat content of 6·5 per cent to be standardized to 3.1 per cent fat using skim
milk containing fat of 0.05 per cent. 8
5.(c)Discuss triode as an amplifier. 8
5.(d)Explain ROM, PROM and EPROM of memory units of computer. 8
5.(e)A single effect evaporator concentrates orange juice at atmospheric pressure of 10130 kPa
from 10 to 50 per cent total soluble solids (w.b.). Saturated steam at 205 kPa is used as
indirect heating system. Calculate the vapour and product flow rates and steam consumption
for a feed rate of 7 kg/s. Assume only latent heat of condensation is available for heating
and feed rate that enters· at its boiling point at l00°C. The enthalpies of saturated steam,
condensate and vapour produced are 2707, 503 and 2676 kJ /kg respectively. The heat capacity
value for both feed and output liquid is 4.187 kJ /kgK and latent heat of vaporization at
100°C is 2257 kJ /kg. Assume datum temperature as 100°C. 8
6.(a)Derive an equation for filtration. Discuss filter cake compressibility. 10
Describe belt conveyor and factors that affect belt conveyor design.
A 5m long screw conveyor with 30cm screw diameter 15cm shaft diameter and 28cm screw
pitch rotates at 300 rpm. Calculate the delivery capacity of this screw conveyor in m3/h.
Its actual capacity is 50 per cent of the theoretical capacity. Calculate the actual power
required for transporting wheat of bulk density 770 kg/m3. Assume the material factor to be
0.40 and power transmission efficiency as 50 per cent. 10
6.(c)Explain the method of measuring torque of rotating shafts using strain gauges. 10
6.(d)A certain vegetable of 85 per cent moisture content (w.b.) at 25°C is dried to 85 per cent solid.
The specific heat of vegetable and water is 3.7 and 4·186 kJ /kg°C respectively. The latent heat
of vaporization at 100, 50 and 0°C are 2260, 2380 and 2840 kJ /kg. Find the heat required per
kg of vegetable in the following cases
Case I:If dehydration is carried out at 100°C at atmospheric pressure and
Case II:If freeze drying is to be carried out and product temperature is initially reduced
to 0 degc. 10

Explain how rice bran oil is extracted by solvent extraction method. 10
A food with an initial moisture content of 15 per cent w.b. is dried in a continuous dryer to
attain a final moisture content of 7 per cent w.b. This drying is accomplished by blowing
fresh warm air after it was mixed with same part of the exhaust air (recycled stream)
from the dryer. The absolute humidity of fresh, recycled and mixed air streams are 0.01,
0.1 and 0.03 kg/kg of dry air respectively. For a feed rate of 100 calculate the
required flow rates of fresh and recycled air stream in terms of kg of dry air per hour
and the amount of dried product obtained per hour. 10
Explain with a flow chart how butter is prepared from milk. 10
List different types of active electrical transducers. Explain the purpose for which piezoelectric
transducers are used. Mention their advantages. 10

8.(a)In sieve analysis of com grits with respect to any particular screen opening of the mass fractions
of desired particle size in feed, overflow, underflow streams are 0.47, 0·85 and 0·2 respectively.
The feed rate of the material on the screen is 10 kg/h. Find mass flow rate for the overflow
stream and overall effectiveness of the stream. 10
8.(b)Shelf life of food stored at 30°C is 7 days. Assuming that Q10 value of deteriorative reactions
occuring in the food is 1·8, estimate the shelf life when it is stored at l0°C. 10
8.(c)Why sugar cane bagasse is best suited for paper making 10
8.(d)It is found that the energy required to reduce particles from a mean diameter of 10 mm to 3 mm
is 10 kJ /kg. Using Rittinger's law, calculate the energy required to reduce the same material from
a diameter of 1 mm to 0·3 mm. 10